radwebster

the crossmember running under my oil pan is breaking off on the driver's side. mine is a '79, and my shopteacher's '76 had the same problem. he says that the force of the motor causes it to flex and bend slightly in that spot, eventually breaking off. it has bent and cracked along where it welds to the frame rail. about 50 percent of the member has already seperated from the rail, and the crossmember is bent.
now, my teachers says that because the metal has flexed back and forth so much, that i need to have about 2 feet of section replaced, right where the a-arms mounts. he says that just welding it again would leave very weak metal there, which would break again.
also, my vette pulls very, very strongly to the left. if i let off the wheel, it could almost spin out by itself. this is due to the frame being damaged, so i would like to get this fixed as soon as possible.

any advice? anyone else have this happen? do you people think that i would need to replace that section near the a-arm? also...what it all boils down to...how much you think this repair will cost? :confused:
thanks

mrvette

Get a good welder in there who knows what he is doing, and he will TIG weld it just fine....nothing super major, unless a whole bunch of metal is torn....like in an accident...you may want to inspect a whole lot of thing under there...pulling the way you describe is dangerous as hell, and you may have accident/rust damage.....something is badly RONG!!!

GENE

Restorer

Gene,
I am curious why do you say TIG. I am just about to do some welding (lower control arm bracket and full seam weld) and I have a MIG but no TIG. I talked to a couple of shops that weld vette frames and they say that they use a MIG. I understand that TIG is better in about all other respects except speed and cost of equipment, but do you really need TIG?
Thank you much!

Mystery Machine

I've never heard of that kind of thing happening on it's own. Maybe as the result of rust or an accident (as stated previously) but not on its own. :confused: Can you replace the whole cross member? :confused:

MikeC

My vette is starting this too. I welded it up last year with MIG and no problems a year later

IF welded properly the weld area will be stronger than the rest of the area. A proper weld shouldl never break, the area around it will.

mrvette

Restorer, I am certainly NOT any welding/metal expert, I just do what my buddy says....he is a Navy cert pipe welder....I forget the term, but something to do with hulls....is his MOS.....at any rate, he TIGS everything....
well, allmost....he also has stick capability...
He MAY apporve of MIG in your case....but I dunno.....all I know is that MIG seems to leave a mess, and TIG .looks like a row of dimes.....

GENE

Twin_Turbo

Yeah it's pretty common, even on the later frames that have gussets around the lower arm mounts to helpprevent this. IT's caused by flexing in the frame and this is where a shock tower brace will do very good to help prevent it.

Here's another prime example of this problem area:

RMVette

Is this something we can all expect to happen at one time or another? This picture show no rust so it's definately from flexing? First I've heard of this and now something else to worry about! :seeya

adamdinat

Thanks for the thread. I need to go home and check this. You should not have to replace anything but may want to add addtional support to reduce the flexing.

NHvette

:iagree:
I would likely weld the existing plate into place - grind it down - and put
another plate over this (extending well over the crossmember). Another
layer of 1/8 or even 1/16 would help greatly. Adding the gussets and
tower brace will help greatly.

The MIG and TIG are nearly identical in what they do. TIG uses a Tungsten
electrode that casts an arc to heat the material. A shielding gas is used to
keep Oxygen (and other impurities) from entering the molten metal. A piece
of welding wire is fed by hand, similar to an OXY/Acetylene weld. The MIG
uses the wire as an electrode. A shielding gas is provided to the weld area,
and the welder has a feed motor that pushes the wire out at a certain rate
(usually adjustable). The only difference is that the MIG pushes the wire for
you, and the arc is struck from the wire itself. In my opinion, a MIG welder
- in the hands of a well trained and experienced professional - can produce
the same quality welds that can be done with a TIG in the same hands. The
start of the weld may be a bit messy with the MIG - as the metal has not
been heated much - but the wire is fed anyway. Once you start to progress,
the results should be the same.

Now, many may have seen the result of MIG welding with a flux-core wire.
This is essentially arc (stick) welding on a smaller wire-fed scale. I do use
the flux core wire - and it does get a bit messy with the flux residue and spatter.

radwebster

thanks guys, i'm gonna have to start pricing it out, as this and my jb welded block are what worries me the most. :smash: :smash:

Wrencher

Very common. also, check the area of lower control arm mount at the cross, member. These bust out as well. I just did this exact repair (upper and lower) on a '73 with a wire feed (MIG) welder. Came out great. The upper control arm brace solves this, and I believe it fits with the stock fan on a SB. Oh, and by the way, DON'T drive it 'till it's fixed! :nono:

Hans

radwebster

don't drive it until it is fixed?!?!?!?! :eek: :eek:

this has been my daily driver for the last 3 weeks...so far so good. i guess that's not the best attitude to have, but my datsun is under repair at the moment. i'm looking for a competent welder as we speak though...we'll see what happens :lurk:

Paul L

Yes do get it fixed ASAP!!

Wrencher

Paul79 illustrates the lower tear very well! I have a template for a re-enforcing plate for that lower frame area if you want or need it...

Hans

Twin_Turbo

can you send me the template?? I am working on my frame and a littlestrengthening there wouldn't be a bad thing.

MikeC

I'd love the template too..... I have a bare frame that I'm starting to play with so this is the perfect time!

virtue4u

I think it is common. I have a non-rusted frame with the same type of crack; however, fortunately for me, I found the crack before it had advanced as much as your picture shows on your car. Everyone should probably check with a mirror and magnifying glass the frame area in the front portion of the car. I had an experienced welder weld it up with a MIG welder. YOu need to clean it up good and slightly, ever so slightly, try to put a "V" in the crack with a dremel tool so that you can get some weld material in the crack. Don't worry. It can be fixed. Just make sure that you do not have any sparks come into contact with gasoline fumes. I agree that you can make the frame stronger with a proper weld.

gdh

:iagree: and disconnect your battery before you start as well.